As is known, discharge into the atmosphere of certain refrigerants, such as those that contain fluorocarbons, is considered to be undesirable for the environment in that they may contribute to the so-called green house effect and/or the degradation of the ozone layer. Fluorocarbons containing refrigerants have often been used in vehicular applications where weight and size are substantial concerns. However, this results in leakage of the undesirable refrigerant to the atmosphere in many vehicular air conditioning systems because such systems typically employ a compressor that requires rotary power by a belt or the like from the engine of the vehicle and as a result can not be hermetically sealed, as in stationary systems. Accordingly, it would be desirable to provide a refrigeration system for use in vehicular applications where any refrigerant that escapes to the atmosphere would not be as potentially damaging to the environment as the refrigerants currently employed, and wherein the components of the refrigeration system remain relatively small and lightweight so as to minimize any adverse consequences on fuel economy for the vehicle.
One type of system considered for vehicular applications is a transcritical carbon dioxide (CO2) system. One benefit of such systems is that the CO2 utilized as a refrigerant can initially be claimed from the atmosphere, so that if it eventually leaks from the system, there is no net increase in atmospheric CO2 content. Further, while CO2 can be undesirable from the standpoint of the greenhouse effect, it does not affect the ozone layer and its use as a refrigerant should not cause an increase in the greenhouse affect since, as just mentioned, there will be no net increase in atmospheric CO2 as a result of leakage.
In transcritical CO2 air conditioning systems, it is often desirable to employ a so-called “suction line heat exchanger” to increase the effectiveness of the transcritical cycle by transferring heat from the refrigerant on the high pressure side of the system to the refrigerant on the low pressure side of the system. However, the addition of a suction line heat exchanger to the vehicle has the potential for increasing weight, as well as consuming more of the space allocated for the air conditioning system in the vehicle. Accordingly, there is a need for a relatively compact and lightweight suction line heat exchanger.